This application claims the benefit of Korean Patent Application No. 2002-53902, filed on Sep. 6, 2002, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference.
1. Field of the Invention
The present invention generally relates to a writing implement having a structure that advances and retreats a bar type lead element into or out of a container, and more particularly, it relates to a writing implement having a structure that enables simple manufacturing process and automation of the manufacturing line, the writing implement having a tip end of the lead element molded into a smooth and complete shape, and the writing implement having a bar type lead element rendering no waste during advance and retreat, and a molding method of the lead element therein.
2. Description of the Prior Art
Generally, a writing implement having a bar type lead element therein has a structure in which the lead element is movably disposed inside of a column type hollow container to be advanced and retreated. When in use, the lead element is advanced out of the container, and then retreated into the container after the writing is finished.
For the advance and retreat of the lead element, the conventional writing implement includes a lead element supporting means that is linearly moved along the inside of the container, and an adjustment means that is rotatably connected to an end of the container and screw-engaged with the lead supporting means. Meanwhile, provided on the outer circumference of the lead supporting means are a plurality of grooves, while a plurality of corresponding protrusions are formed on the inner circumference of the container in an axial direction. Accordingly, as the protrusions are slid along in contact with the grooves, the lead supporting means is moved inside of the container in a linear direction.
Since the lead supporting means is screw-engaged with the adjustment means, the lead supporting means is subject to a propelling force in the axial direction when the adjustment means is rotated. And since the protrusions of the lead supporting means are in contact with the grooves of the container, the lead supporting means is linearly moved inside of the container in an axial direction, instead of being rotated. Accordingly, the bar type lead element, which is connected with the lead supporting means, is either advanced out, or retracted into the container.
Meanwhile, the bar type lead element is shaped by cooling thus solidifying the high temperature raw material in melt state at a room temperature. More specifically, a nozzle is inserted into the container to inject the melt raw material therethrough. Then by cooling the raw material in the container, the raw material solidifies into the shape identical to that of the interior of the container.
One example of conventional method of forming the lead element for the writing implement is as follows. First, with the lead supporting means being assembled with the adjustment means, the assembled lead supporting means and the adjustment means are connected to the rear end of the container. Next, the container is made stand upright with its front end facing upward, and the nozzle is inserted into the container through the front end of the container. Then, the raw material in melt state is injected into the container through the nozzle, and solidifies into the complete lead element.
However, according to the conventional method for forming the lead element, after the solidification of the raw material, the leading end of the lead element is formed plane. As the plane tip end of the lead element is not appropriate for writing, it is necessary to sharpen the leading end of the lead element. Accordingly, the manufacturing process becomes complex, and the automation of the manufacturing process is hardly achieved.
As another example of the conventional method of forming the lead element, there was a method that a pointed cap is connected to the front end of the container and the container is made stand upright with its front end and the pointed cap facing downside. Then the nozzle is inserted into the container through the rear end of the container, and the raw material in melt state is injected through the nozzle and solidifies therein.
By the above method, since the leading end of the lead element is formed inside of the pointed cap into a rounded point, requirements for the process of sharpening the leading end of the lead element after the solidification can be omitted. However, this method has the following drawbacks.
According to the second example of the conventional lead element forming methods, the lead supporting means is assembled in the container only after the injection of the melt raw material. Accordingly, the lead supporting means has to be assembled in the container immediately after the injection of the raw material into the container. The problem is that the assembling process of the lead supporting means and the container requires manual work, as it requires personal attention to accurately fit the grooves on the outer circumference with the protrusions formed on the inner circumference of the container. In other words, the assembling process can hardly be automated, and thus, efficiency in this process cannot be expected.
Further, in the case that the assembling of the lead supporting means is delayed, i.e., in the case that the lead supporting means is assembled after the raw material already solidifies to some extent, the lead supporting means and the container can be assembled incompletely, and as a result, the lead element can not be supported stably by the lead supporting means. With the lead element being supported by the lead supporting means unstably, the lead element is easily escaped out of the lead supporting means during the retreat because of the frictional force generated between the outer circumference of the lead element and the inner circumference of the container.
Meanwhile, the conventional writing implement constructed as above also has a problem of having a waste, such as the scrapes of the lead element during a movement of the lead element by the friction with the inner surface of the container.
More specifically, the conventional writing implement has the protrusions formed in an axial direction along the inner circumference of the container, another protrusions formed on the outer circumference of the lead supporting means for being connected with the protrusions of the container, and still another protrusions formed in an axial direction along the outer circumference of the lead element that has the corresponding shape as that of the inner circumference of the container. Further, being screw-engaged with the adjustment means, the lead supporting means is subject to the rotational force as well as to the propelling force when the adjustment means is rotated. The rotational force is exerted to the lead supporting means in a forward direction when the lead element is advanced, and then exerted in the opposite direction when the lead element is retreated. Meanwhile, the grooves of the lead supporting means and the protrusions of the container are formed at certain clearance. Accordingly, during the advance and retreat of the lead element, the lead element is subject to a pressure by the protrusions of the container in one and opposite directions as much as the distance of the clearance. As the lead element is pushed against the grooves, the lead element often collapses or its outer surface breaks off.
Further, the outer circumference of the lead element is concaved for an engagement with the inner circumference of the container. Thus, when the lead element is advanced out of the container, the writing implement has a degraded appearance due to such concaved surface.
The present invention has been made to overcome the above-mentioned problems of the prior art, and accordingly, it is an object of the present invention to provide a writing implement enabling a simple manufacture and an automation of assembly line by having all the required parts being assembled in place when injecting a raw material in melt state into a container, and starting charging of the raw material from an inner end of a cap, and a method of forming the lead element therein.
The above object is accomplished by a writing implement having a bar type lead element according to the present invention, including a bar type lead element being formed as a raw material in melt state solidifies, a container formed as a hollow member having one and opposite ends being open; a supporting shaft inserted in the container to be moved therein linearly in an axial direction, the supporting shaft being formed as a hollow member having a center hole pierced therethrough; and an adjustment member movably connected to a rear end of the container to be rotated, the rotation of the adjustment member causes the supporting shaft to be linearly moved in the container, the adjustment member being formed as a hollow member having one and opposite ends being open to be in fluid communication with the center hole 42. The raw material of the lead element is injected into the container from a rear end of the adjustment member through the center hole, and solidifies into the lead element, and the lead element is supported on the front end of the supporting shaft at its rear end, and moved in accordance with the movement of the supporting shaft.
The supporting shaft is screw-engaged with the adjustment member to be linearly moved in the axial direction inside of the container in accordance with the rotational movement of the adjustment member.
More specifically, the supporting shaft includes a shaft portion having a spiral groove formed in an outer circumference, and a supporting portion connected to a front end of the shaft portion with an outer circumference being in contact with the inner circumference of the container and not allowed to rotate but only allowed to move in a linear direction, while the adjustment member includes a spiral protrusion formed in a front end for being inserted in the spiral groove. Accordingly, as the spiral protrusion moves along the spiral groove by the rotation of the adjustment member, and the supporting shaft is not rotated but moved linearly in the axial direction inside of the container.
Since the outer circumference of the supporting portion and the inner circumference of the container are formed in a polygonal shape, the supporting portion, being inserted in the container, is only allowed to move in the axial direction.
The supporting portion includes an accommodating recess for accommodating a rear end of the lead element, and a through hole in fluid communication with the accommodating recess, the accommodating recess and the through hole being filled with a raw material of the lead element.
Further provided is a cap formed as a hollow member having an open rear end and a closed front end, for accommodating the container therein. The cap includes a recess formed in an inner side of the front end, having a shape corresponding to a shape of the leading end of the lead element.
According to the present invention, the writing implement can further include a plug for sealing the rear end of the adjustment member, the plug having a projection protruding from the center for being inserted into the center hole of the supporting shaft.
The above object is also accomplished by a method for forming a lead element according to the present invention, including the steps of: rotatably assembling an adjustment member to a rear end of a container, the container being formed as a hollow member having one and the opposite end open, the adjustment member being formed as a hollow member having one and the opposite end open; inserting a supporting shaft in the container from the front direction in a manner such that the supporting shaft is moved in the container, the supporting shaft being formed as a hollow member having a hole being pierced therethrough; screw-engaging the adjustment member with the supporting shaft in a manner such that the supporting shaft is linearly moved in the container in accordance with the rotation of the adjustment member; sealing the container by covering the front end of the container with a cap; inserting a nozzle in the container through the supporting shaft from the rear direction of the adjustment member, the nozzle for injection of a raw material of the lead element in melt state; injecting the raw material of the lead element in melt state in the container through the nozzle; and forming a bar type lead element by solidifying the raw material of the lead element injected into the container.
The lead element is formed in the shape corresponding to the inner shape of the container, with a leading end being formed in accordance with a recess of the cap that is formed in an inner side of an end of the cap, and a rear end being secured to the front end of the supporting shaft.
In the raw material injection step, the raw material of the lead element in melt state is injected into the container, with the nozzle, which is inserted to the proximity of the front end of the container, being retreated from the proximity of the front end of the container to the front end of the supporting shaft.
After the injection of the raw material, the rear end of the adjustment member is sealed by a plug.
With the writing implement having the bar type lead element and the molding method of the lead element therein according to the present invention, the raw material in melt state can be injected with all the main parts, i.e., the supporting shaft, the adjustment member and the cap, being assembled with the container. As a result, the manufacturing process becomes simplified, and the automation of assembly line can be achieved easily.
Further, according to the present invention, the recess having a certain configuration desired for the shape of the leading end of the lead element is formed in the inner side of the end of the cap. As the raw material is injected in the container, it enables easy achievement of the simplification of the manufacturing process and assembly line automation. Additionally, the leading end of the lead element can be molded to have a smooth and complete shape as that of the configuration of the recess of the cap.
In the writing implement according to the present invention, the supporting shaft and the lead element have the polygonal sections corresponding to the inner configuration of the container. As the supporting shaft and the lead element are connected in the container to be movable therein and with the polygonal sections thereof being aligned with one another, the lead element does not experience excessive pressure during advance and retreat, and as a result, deformation of the lead element and the undesired fragment of the lead element from the breakage, can be prevented.